We have pursued our analysis of the anti-inflammatory properties of heparin, depleted of anticoagulant activity and administered orally or intravenously on delayed-type hypersensitivity reactions, and demonstrated its interference with the migration of inflammatory cells into the challenged site. We have documented the influence that immunoglobulin-bearing B cells have on the development of the suppressor T-cell repertoire by demonstrating the role of Ig-bearing B cells on the development of T-cell idiotypes. A requirement for an intracellular processing step by accessory cells previous to antigen presentation to T cells was demonstrated for a broad group of native antigens, among which were the determinants of Listeria monocytogenes and hen egg liposome. The suppression by T cells of immunoglobulin synthesis by mouse myeloma was subjected to further study. The molecular parameters essential for the initiation of secondary in vitro allogeneic cytolytic T-cell response to Class I MHC antigens were investigated using purified antigens and liposomes. The density of H-2 proteins was found to be essential for effective recognition. (MB)